Xaaron was one of two brothers that were under The Fallen's command as Heralds of Unicron. He fed Xintun to The Fallen after Ynot had used a mask to turn him into a Hollow. After all of those events had been undone by Blackout's abuse of the Vahi Cube, Ynot had the Toa Idiotas find Xaaron in order to summon the Fallen to aid him in the fight against Blackout. When Unicron was finally resurrected, Xaaron was summoned along with seven other Heralds to go after Zev Raregroove, Namah, Ryoko and Washu. He and all the other Heralds were killed by Tokimi.